ASTM B784-01(2012)
(Specification)Standard Specification for Modified Concentric-Lay-Stranded Copper Conductors for Use in Insulated Electrical Cables
Standard Specification for Modified Concentric-Lay-Stranded Copper Conductors for Use in Insulated Electrical Cables
ABSTRACT
This specification covers bare modified concentric-lay-stranded conductors made from round copper wires, either uncoated or coated with tin, lead, or lead alloy for general use in insulated electrical cables. These conductors shall be constructed with a central core consisting of not more than seven wires, surrounded by one or more layers of helically laid wires. For the purposes of this specification, conductors are classified as Class B modified, class C modified, and Class D modified. The conductors shall meet the prescribed construction requirements such as number of wires and diameter. Welds and brazes may be made in rods or in wires prior to final drawing. Welds and brazes may be made in the finished individual wires composing the conductor, but shall not be closer together than prescribed distance. Tests for the electrical properties of wires composing conductors made from soft or annealed copper wire, bare or coated, shall be made before stranding. Tests for the physical properties of these materials may be made upon the wires before stranding or upon wires removed from the complete stranded conductor.
SCOPE
1.1 This specification covers bare modified concentric-lay-stranded conductors made from round copper wires, either uncoated or coated with tin, lead, or lead alloy for general use in insulated electrical cables. These conductors shall be constructed with a central core consisting of not more than seven wires, surrounded by one or more layers of helically laid wires.
1.2 For the purposes of this specification, conductors are classified as follows (Explanatory Note 1 and Note 2):
1.2.1 Class B Modified—Conductors to be insulated with various materials such as rubber, paper, and crosslink polyethylene.
1.2.2 Class C Modified and Class D Modified—Conductors where greater flexibility is required than is provided by Class B Modified conductors.
1.3 The values stated in inch-pound or SI units are to be regarded separately as standard. Each system shall be used independently of the other. Combining the values from the two systems may result in non- conformance with the specification. For conductor sizes designated by AWG or kcmil sizes, the requirements in SI units are numerically converted from the corresponding requirements in inch-pound units. For conductor sizes designated by AWG or kcmil, the requirements in SI units have been numerically converted from corresponding values stated or derived in inch-pound units. for conductor sizes designated by SI units only, the requirements are stated or derived in SI units.
1.3.1 For density, resitivity and temperature, the values stated in SI units are to be regarded as standard.
Note 1—The significant differences in this specification from Specification B8 are as follows: (1) The central core is permitted to contain up to seven wires drawn into the assembly with an infinite length of lay while Specification B8 permits only one, and (2) The construction is applicable only to stranded assemblies of 19 or more wires.
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Designation: B784 −01 (Reapproved 2012)
Standard Specification for
Modified Concentric-Lay-Stranded Copper Conductors for
Use in Insulated Electrical Cables
This standard is issued under the fixed designation B784; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This specification covers bare modified concentric-lay- 2.1 The following documents of the issue in effect at the
stranded conductors made from round copper wires, either dateofmaterialpurchaseformapartofthisspecificationtothe
uncoated or coated with tin, lead, or lead alloy for general use extent referenced herein.
in insulated electrical cables. These conductors shall be con-
2.2 ASTM Standards:
structed with a central core consisting of not more than seven
B3 Specification for Soft or Annealed Copper Wire
wires, surrounded by one or more layers of helically laid wires.
B8 Specification for Concentric-Lay-Stranded Copper
1.2 For the purposes of this specification, conductors are Conductors, Hard, Medium-Hard, or Soft
B33 Specification for Tin-Coated Soft or Annealed Copper
classified as follows (Explanatory Note 1 and Note 2):
Wire for Electrical Purposes
1.2.1 Class B Modified—Conductors to be insulated with
B189 Specification for Lead-Coated and Lead-Alloy-Coated
various materials such as rubber, paper, and crosslink polyeth-
Soft Copper Wire for Electrical Purposes
ylene.
B263 Test Method for Determination of Cross-Sectional
1.2.2 Class C Modified and Class D Modified—Conductors
Area of Stranded Conductors
where greater flexibility is required than is provided by Class
B354 Terminology Relating to Uninsulated Metallic Electri-
B Modified conductors.
cal Conductors
1.3 The values stated in inch-pound or SI units are to be
2.3 Other Standard:
regarded separately as standard. Each system shall be used
NBS Handbook 100
independently of the other. Combining the values from the two
systems may result in non- conformance with the specification.
3. Ordering Information
For conductor sizes designated by AWG or kcmil sizes, the
requirements in SI units are numerically converted from the
3.1 Orders for material under this specification shall include
correspondingrequirementsininch-poundunits.Forconductor
the following information:
sizesdesignatedbyAWGorkcmil,therequirementsinSIunits
3.1.1 Quantity of each size and class,
have been numerically converted from corresponding values
3.1.2 Conductor size: circular-mil area or American Wire
stated or derived in inch-pound units. for conductor sizes
Gage (AWG) (Section 6),
designated by SI units only, the requirements are stated or
3.1.3 Class (see 1.2 and Table 1),
derived in SI units.
3.1.4 Temper (see 10.2),
1.3.1 For density, resitivity and temperature, the values
3.1.5 Whether coated or uncoated; if coated, designate type
stated in SI units are to be regarded as standard.
of coating (see 10.1 and 10.2),
NOTE 1—The significant differences in this specification from Specifi- 3.1.6 Details of special-purpose lays, if required (see 5.2),
cation B8 are as follows: (1)The central core is permitted to contain up to
3.1.7 Lagging, if required (see 14.2),
seven wires drawn into the assembly with an infinite length of lay while
3.1.8 Special package marking, if required (Section 13),
Specification B8 permits only one, and (2) The construction is applicable
only to stranded assemblies of 19 or more wires. 3.1.9 Place of inspection (Section 12), and
1 2
This specification is under the jurisdiction of ASTM Committee B01 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Conductors of Copper and Copper Alloys. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 1, 2012. Published August 2012. Originally the ASTM website.
approved in 1988. Last previous edition approved in 2006 as B784 – 01 (2006). Available from National Technical Information Service (NTIS), 5285 Port
DOI: 10.1520/B0784-01R12. Royal Rd., Springfield, VA 22161, http://www.ntis.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B784 − 01 (2012)
TABLE 1 Construction Requirements of Modified Concentric-Lay-Stranded Copper Conductors
NOTE 1—See Explanatory Note 5.
Size Class B Modified Class C Modified Class D Modified
Circular Mils American Number of Diameter Number of Diameter Number of Diameter
Wire Gage Wires (mils) (mm) Wires (mils) (mm) Wires (mils) (mm)
A
5 000 000 217 151.8 3.86 271 135.8 3.45 271 135.8 3.45
4 000 000 217 144.0 3.66 271 128.9 3.27 271 128.9 3.27
4 000 000 217 135.8 3.45 271 121.5 3.09 271 121.5 3.09
3 500 000 169 143.9 3.66 217 127.0 3.23 271 113.6 2.89
A
3 000 000 169 133.2 3.38 217 117.6 2.99 271 105.2 2.67
A
2 500 000 127 140.3 3.56 169 121.6 3.09 217 107.3 2.73
A
2 000 000 127 125.5 3.19 169 108.8 2.76 217 96.0 2.44
1 900 000 127 122.3 3.11 169 106.0 2.69 217 93.6 2.38
1 800 000 127 119.1 3.03 169 103.2 2.62 217 91.1 2.31
A
1 750 000 127 117.4 2.98 169 101.8 2.59 217 89.8 2.28
1 700 000 127 115.7 2.94 169 100.3 2.55 217 88.5 2.25
1 600 000 127 112.2 2.85 169 97.3 2.47 217 85.9 2.18
A
1 500 000 91 128.4 3.26 127 108.7 2.76 169 94.2 2.39
1 400 000 91 124.0 3.15 127 105.0 2.67 169 91.0 2.31
1 300 000 91 119.5 3.04 127 101.2 2.57 169 87.7 2.23
1 250 000 91 117.2 2.98 127 99.2 2.52 169 86.0 2.18
1 200 000 91 114.8 2.92 127 97.2 2.47 169 84.3 2.14
1 100 000 91 109.9 2.79 127 93.1 2.36 169 80.7 2.05
A
1 000 000 61 128.0 3.25 91 104.8 2.66 127 88.7 2.25
900 000 61 121.5 3.09 91 99.4 2.52 127 84.2 2.14
A
800 000 61 114.5 2.91 91 93.8 2.38 127 79.4 2.02
A
750 000 61 110.9 2.82 91 90.8 2.31 127 76.8 1.95
A
700 000 61 107.1 2.72 91 87.7 2.23 127 74.2 1.88
650 000 61 103.2 2.62 91 84.5 2.15 127 71.5 1.82
A
600 000 61 99.2 2.52 91 81.2 2.06 127 66.7 1.69
550 000 61 95.0 2.41 91 77.7 1.97 127 65.8 1.67
A
500 000 37 116.2 2.95 61 90.5 2.30 91 74.1 1.88
450 000 37 110.3 2.80 61 85.9 2.18 91 70.3 1.79
A
400 000 37 104.0 2.64 61 81.0 2.06 91 66.3 1.68
A
350 000 37 97.3 2.47 61 75.7 1.92 91 62.0 1.57
A
300 000 37 90.0 2.29 61 70.1 1.78 91 57.4 1.46
A
250 000 37 82.2 2.09 61 64.0 1.63 91 52.4 1.33
A
211 000 0000 19 105.5 2.68 37 75.6 1.92 61 58.9 1.50
A
167 000 000 19 94.0 2.39 37 67.3 1.71 61 52.4 1.33
A
133 000 00 19 83.7 2.13 37 60.0 1.52 61 46.7 1.19
A
105 000 0 19 74.5 1.89 37 53.4 1.36 61 41.6 1.06
A
83 000 1 19 66.4 1.69 37 47.6 1.21 61 37.0 0.94
A
These sizes of conductors provide for one or more schedules of preferred series and commonly are used in the industry. The sizes not marked are given simplyasa
matter of reference and it is suggested that their use be discouraged.
4. Joints 5.2 Other lays for special purposes shall be furnished by
special agreement between the manufacturer and the purchaser
4.1 Welds and brazes may be made in rods or in wires prior
(Explanatory Note 3).
to final drawing.Welds and brazes may be made in the finished
individual wires composing the conductor, but shall not be 5.3 The direction of lay of the outer layer shall be left-hand
closer together than prescribed in Table 2. unless the direction of lay is specified otherwise by the
purchaser.
5. Lay
5.4 The direction of lay shall be reversed in successive
5.1 The lay of a layer of wires shall be not less than eight
layers, unless otherwise specified by the purchaser.
nor more than sixteen times the outside diameter of that layer,
6. Construction
except that for conductors composed of 37 wires or more, this
requirement shall apply only to the two outer layers.The lay of 6.1 The areas of cross section, numbers, and diameters of
the layers other than the two outer layers shall be at the option wires in the various classes of concentric-lay-stranded conduc-
of the manufacturer, unless otherwise agreed upon. tors shall conform to the requirements prescribed in Table 1.
6.2 The diameters of the wires listed in Table 1 are nominal.
Where“combinationstrand’’isrequiredinordertoinsulatethe
TABLE 2 Minimum Distance Between Joints in the Completed
conductor properly (strands in the outer layer having a larger
Conductor
diameter than those in the inner layers) the diameters shall be
Number of Wires in Conductor Soft All Classes
19 1 ft subject to a tolerance of 6 5 %, provided that the area of cross
A
20 and over 1 ft in a layer
section after stranding is in accordance with Section 11.
A
Except as indicated, the limitations apply to closeness of joints throughout the
6.3 Where compressed stranding is required in order to
completed conductor.
insulate the conductor properly, one or more layers of any
B784 − 01 (2012)
TABLE 3 Standard Increments Due to Stranding
stranded conductor consisting of 19 wires or more may be
slightly compressed, thereby reducing the outside diameter of Increment of Resistance
Type of Conductor
and Mass, %
the conductor by not more than 3 %, provided that the area of
Classes B Modified, C Modified, and D 2
cross section after stranding is in accordance with Section 11.
Modified, 2 000 000 cmil and under
Over 2 000 000 to 3 000 000 cmil 3
Over 3 000 000 to 4 000 000 cmil 4
7. Physical and Electrical Tests of Stranded Conductors
Over 4 000 000 to 5 000 000 cmil 5
of Soft Wires
7.1 Tests for the electrical properties of wires composing
conductors made from soft or annealed copper wire, bare or
10. Requirements for Wires
coated, shall be made before stranding.
10.1 The purchaser shall designate the type of wire and the
7.2 Tests for the physical properties of soft or annealed
kind of coating, if any, to be used in the conductor.
copper wire, bare or coated, may be made upon the wires
10.2 Beforestranding,thecopperwireusedshallmeetallof
before stranding or upon wires removed from the complete
the requirements of ASTM Specifications B3, B33, and B189
strandedconductor,butneednotbemadeuponboth.Careshall
that are applicable to its type.
be taken to avoid mechanical injury to wire removed from the
conductor for the purpose of testing.
10.3 Thecentralcoreshallbemadeofwireofthesametype
and temper as the concentric layers, unless otherwise specified.
7.3 The physical properties of wires when tested before
stranding shall conform to the applicable requirements of 10.2.
11. Variation in Area
7.4 The physical properties of wires removed from the
11.1 The area of cross section of the completed conductor
completed stranded conductor shall be permitted to vary from
shall be not less than 98 % of the area indicated in Column 1
the applicable requirements of 10.2 by the following amounts
of Table 1. Unless otherwise specified by the purchaser, the
(Explanatory Note 4):
manufacturer may have the option of determining the cross-
7.4.1 Average of Results Obtained on All Wires Tested—The
sectional area by either of the following methods; except that
minimum elongation required shall be reduced in numerical
in case of a question regarding area compliance, the method of
value 5 (for example, from 30 to 25 %) from the numerical
11.1.2 shall be used.
requirements for the wire before stranding.
11.1.1 The area of cross section of a conductor may be
7.4.2 Results Obtained on Individual Wires—Theelongation
determined by calculations from diameter measurements, ex-
ofindividualwiresshallbereducedinnumericalvalue15from
pressed to four decimal places, of its component wires at any
the minimum requirements before stranding (that is, 10 in
point when measured perpendicularly to their axes.
addition to the 5 allowed in 7.4.1), but in no case shall the
11.1.2 The area of cross section of a conductor may be
elongation of any individual wire be less than 5 %.
determined byTest Method B263. In applying that method, the
7.5 In the event that the requirements prescribed in 7.4.2 are increment in mass resulting from stranding may be the appli-
cable value specified in 9.1 or may be calculated from the
met but those prescribed in 7.4.1 are not met, a retest shall be
permitted wherein all wires of the conductor shall be tested for measured component dimensions of the sample under test. In
case of a question regarding area compliance, the actual mass
the purpose of final determination of conformance to 7.4.
increment due to stranding shall be calculated.
7.6 Elongation tests to determine compliance shall not be
made on the conductor as a unit (Explanatory Note 6).
12. Inspection
7.7 If a tinning, lead-coating, or lead-alloy-coating test is
12.1 Unless otherwise specified in the contract or purchase
required, it shall be made on the wires prior to stranding.
order, the manufacturer shall be responsible for the perfor-
mance of all inspection and test requirements specified.
8. Density
12.2 All inspections and tests shall be made at the place of
8.1 For the purpose of calculating mass per unit length,
manufactureunlessotherwiseagreeduponbythemanufacturer
cross sections, etc., the density of the copper shall be taken as
and the purchaser at the time of purchase.
3 3
0.32117 lb/in. or 8.89 g/cm at 20°C (Note 2 and Explanatory
12.3 The manufacturer shall afford the inspector represent-
Note 7).
ing the purchaser all reasonable manufacturer’s facilities to
NOTE 2—The term “mass” is being used in this specification as being
satisfy that the material is being furnished in accordance with
more technically correct. It replaces the term “weight.”
this specification.
9. Mass and Resistance 13. Product Marking
9.1 The mass and electrical resistance of a unit length of 13.1 The net mass, length (or lengths and number of
stranded conductor are a function of the length of lay. The lengths, if more than one length is included in the package),
approximate mass and electrical resistance may be determined size, kind of conductor, purchase order number, and any other
using the standard increments shown in Table 3. When greater marks required by the purchase order shall be marked on a tag
accuracy is desired, the increment based on the specific lay of attached to the end of the conductor inside of the package. The
the conductor may be calculated (Explanatory Note 8). same information, together with the manufacturer’s serial
B784 − 01 (2012)
number (if any) and all shipping marks required by the 14.2 The conductors shall be protected against damage in
purchaser, shall appear on the outside of each package. ordinary handling and shipping. If
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